cc: Nathan Gillett <n.gillett@uea.ac.uk>, Gabi Hegerl <gabi.hegerl@ed.ac.uk>, Peter Stott <stott.peter@googlemail.com>, Toru Nozawa <nozawa@nies.go.jp>, Alexey Karpechko <A.Karpechko@uea.ac.uk>, Michael Wehner <MFWehner@lbl.gov>
date: Thu Dec  4 14:29:16 2008
from: Phil Jones <p.jones@uea.ac.uk>
subject: Re: Fwd: draft Communication Arising   regarding  your recent
to: Dith Stone <stoned@csag.uct.ac.za>

    Daithi,
       No myth - it's true and applies to ERA-40 as well.
    They do have SSTs changing - so they get a bit of the anthro signal that way.
    There is a Nature comment (Trenberth) on Kalnay and Cai (2003) referred to in Ch 3 of AR4.
     Calculating the PDO and AMO from SST means you'll get some upward trend as well.
    The more I think about this comment - the poorer it gets.
    Cheers
    Phil
   At 14:03 04/12/2008, Dith Stone wrote:

     I seem to remember something about the NCEP reanalysis having constant GHG
     concentrations, but maybe this is just an urban myth?
     DA
     On Thu, 4 Dec 2008, Phil Jones wrote:

      Nathan,
         A few thoughts.
        First - most odd that they go on about the Arctic. The warming here is much
     clearer
      and the sea ice is disappearing in summer!  I can't see their comment getting past
     reviewers.
        All of the Arctic and Antarctic stations are manned - at least at the
      moment. Even though they are manned, the equipment might be automatic, in that
     readings
      can be made without going out into the cold!
         You can't use Reanalyses in the Arctic and especially the Antarctic as they are
      way off from the observations (Simmons et al., 2004), especially before the
     satellite
      era in 1979. The reason they are way off from the obs is that before the satellite
      era there aren't enough data to overcome model biases. In the Antarctic (fig 6 in
      Simmons et al) most of the obs get rejected as they are so far away from the
     model's
      wrong first guess.
         You could suggest that they work out (from the Reanalysis - it doesn't matter
     that it's
      wrong) how representative the limited Antarctic temperature stations are of the
     continental
      average - at the 5 year scale. They will be surprised by the result. A limited
     number of
      stations works quite well at this timescale. Suggest they read this paper (Jones et
     al. 1997)
      on this. They are confused by daily timescales and the 5-year averages we are
     looking at.
      The comparison to Italy is ridiculous. At the 5-year timescale, probably just one
     or two Italian
      sites would be all that was needed. The issue here is how many spatial degrees of
     freedom
      there is - and this depends on timescale.
        You have pointed out that their regressions with PDO and AMO are not very clever.
     They
      are going to be losing temporal degrees of freedom with their lagged regressors. I
     bet
      they are not reducing degrees of freedom because of autocorrelation either. It is
     quite
      easy to take any temperature series and show that it can be related to circulation
      indices. Just because the circulation explains more variability than the climate
     models
      doesn't mean that anthropogenic climate change isn't happening. What is causing the
      circulation to change!
        Maybe you could add a few references where you've shown D&A for the NAM and the
     SAM.
      Anyone tried the AMO or the PDO.
      Cheers
      Phil
      PS Your grant has just paid the page charges from Nature Geosciences!
     Jones, P.D., Osborn, T.J. and Briffa, K.R., 1997:  Estimating sampling errors in
     large-scale temperature averages.  J. Climate 10, 2548-2568.
     Simmons, A.J., P.D. Jones, V. da Costa Bechtold, A.C.M. Beljaars, P.W. Kllberg, S.
     Saarinen, S.M. Uppala, P. Viterbo and N. Wedi, 2004: Comparison of trends and
     low-frequency variability in CRU, ERA-40 and NCEP/NCAR analyses of surface air
     temperature. J. Geophys. Res., 109, D24115, doi:10.1029/2004JD006306.
     At 21:42 03/12/2008, Nathan Gillett wrote:
           Hi all,
           I was sent the attached draft paper, which the authors say they are
           planning to submit in response to our Nature Geoscience paper, inviting
           our comments. I've drafted a response - see attached. At this stage,
           this probably isn't worth spending a huge amount of time on, but let me
           know if you have further comments.
           Phil - am I correct in writing that the station data used in CRUTEM3
           comes only from manned stations?
           Cheers,
           Nathan
           ---------- Forwarded message ----------
           From: Luigi Mariani <luigi.mariani@unimi.it >
           Date: 2008/12/1
           Subject: draft "Communication Arising" regarding your recent Nature
           Geoscience paper ? please comment
           To: n.gillett@uea.ac.uk
           Cc: Maurizio Morabito <maurizio@morabito.name >, Parisi Simone
           <meteoclima@hotmail.it>, Gabriele Cola <gabriele.cola@unimi.it >, Paolo
           Mezzasalma <pmezzasalma@arpa.emr.it >, Teodoro Georgiadis <
           t.georgiadis@ibimet.cnr.it>
           Dear Dr. Gillett,
           We are a group of climate scientists mostly based in Italy.
           We have read with interest your recent article in Nature Geoscience
           "Attribution of polar warming to human influence" but have some doubts
           regarding your conclusions. We have prepared a draft "Communication
           Arising" for that same publication (enclosed).
           Before we submit our contribution to Nature Geoscience, we would very
           much appreciate your comments about our points, with the aim of
           resolving disputes whenever possible and remove points where we all
           agree.
           We are also sending a spreadsheet with the data and computations needed
           to replicate our findings. Any question you might have, please do not
           hesitate to contact me.
           Thank you in advance. Please note that as per Nature's guidelines, you
           have 2 weeks to respond.
           Best regards.
           Luigi Mariani
           Universit degli Studi di Milano
           Dept. of Crop Science
           Agrometeorology research group
           ------------------------
           Luigi Mariani
           329 7027077 (cellulare)
           02 50316587 (Unimi-DiProVe)
           02 4238410 (studio)
           --
           ****************************************************************************
           Dr Nathan Gillett,
           Canadian Centre for Climate Modelling and Analysis,
           University of Victoria,
           PO Box 3065, STN CSC,
           Victoria, BC, V8W 3V6,
           Canada.
           Tel: (250) 363 8264
           Fax: (250) 363 8247
           Email: Nathan.Gillett@ec.gc.ca
           ****************************************************************************
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           Content-Type: application/msword; name=Mariani_response.doc
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     Prof. Phil Jones
     Climatic Research Unit        Telephone +44 (0) 1603 592090
     School of Environmental Sciences    Fax +44 (0) 1603 507784
     University of East Anglia
     Norwich                          Email    p.jones@uea.ac.uk
     NR4 7TJ
     UK
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   Prof. Phil Jones
   Climatic Research Unit        Telephone +44 (0) 1603 592090
   School of Environmental Sciences    Fax +44 (0) 1603 507784
   University of East Anglia
   Norwich                          Email    p.jones@uea.ac.uk
   NR4 7TJ
   UK
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